The present invention relates to a digital signal processing apparatus, a digital signal processing method, an information center, and a data delivery system for processing signals such as digital audio data.
Customers can acquire audio data including music data in a number of ways. One way is to purchase such storage media as records or compact discs (CD) carrying desired data. Another way is to tune in to radio broadcasts or like transmissions to get desired audio data recorded onto a recordable storage medium.
Recent years have witnessed the launching of a so-called server system scheme selling music data. Under this scheme, large amounts of audio data (music data) are stored on hard disks or like means from which customers may purchase desired music data for transfer to external storage media in their possession.
Under the server system scheme, server systems are set up illustratively at storefronts. A customer with his or her own storage medium (external storage medium) walks up to one of such server systems at a storefront. After paying a required amount, the customer gets desired music data recorded onto the storage medium.
Generally, the music data are held in compressed format in the server system to make the most of the server's storage and data transfer capacities. That means the server system is capable of having requested music data transferred and recorded to the customer's storage medium in a shorter time period than the actual playing time of the music data in question.
When purchasing music data, the customer makes such entries into the server system as the title of desired music data, name of a performer(s), playing time, or other additional information in text format or through an image-driven selection interface. The server system verifies the entries to let the customer retrieve the desired music data easily for recording to his storage medium for enjoyment.
The above type of server system may accommodate a plurality of types of external storage media. Such media may include a small magneto-optical disc known as the MD (Mini-disc) and a semiconductor device called the memory card.
There may be a case in which a user wants to move previously purchased music data from an MD to another storage medium such as a memory card, illustratively because the user's MD player has ceased to be functional. In that case, the user may not be able to copy the data from one of his own storage media to another because of copyright considerations or due to the degradation of sound quality following duplication.
If that happens, the user must purchase again the music data of interest through the server system for recording to the new storage medium. This is disadvantageous to the user who has to buy the same music data just because his old storage medium carrying the previously recorded music data is no longer usable.
There may be a case where the user wants to purchase, using the same storage medium, the same music data in a compressed format offering a better sound quality than in the old compressed format in effect at the time of the preceding purchase. This is also disadvantageous to the user who is required to pay again for the same music data, with the previously purchased music data of lesser sound quality not in use.
There may also be a case in which the user, having used a defective storage medium upon the preceding purchase, wants to have the same music data rerecorded onto the storage medium. In this case, the user must also pay more than once for the same music data from the server system despite the previous legitimate purchase.
One solution to the problems above might involve arranging for each storage medium to retain information for identifying the source (i.e., vendor) from which music data were purchased. The arrangement would allow the user wishing to buy the same music data to do so from the same source free of charge or at a reduced price.
Currently marketed storage media, however, have no storage area for accommodating the information representative of the music data source (vendor). If the source identification information were added from now on to the music data to be purchased and recorded to users' storage media, the users who already possess previously purchased music data on their storage media are also at a disadvantage. That is because the absence of such identification information in the music data in the possession of these users disqualifies them from any new services that may be offered to newcomers.
There is thus a growing need for a music data server system capable of judging easily and unfailingly whether music data found on a given user's storage medium have been legally purchased from a legitimate vendor, so that new services can be offered to legitimate users if they make further purchases from the same vendor.
The criteria for judging whether given data are a legal purchase from a legitimate vendor are fairly straightforward. Illustratively, if a user's data turn out to be a copy of music data purchased by someone else from the server system, or are a duplicate of data from package media such as CDs in the possession of others, the copied data are obviously illegal.